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Premium Member
1997 S600 (sold)
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Discussion Starter #1
I've had the flashing gas gauge and check engine light with P0455 code for several months now. Both indicate a gross leak in the evaporative emissions control system. I finally got around to investigating the problem since I was already digging in my engine compartment to change the intake hoses and clean the throttle bodies. I think I found and fixed the problem. I was hoping it was something simple like a disconnected or damaged hose, and I did find a disconnected hose as I traced the hoses from the throttle bodies backward.

Here are some pictures:

This is the right side showing the throttle body, the evaporative emissions control system hoses which connect to the charcoal canister located in the trunk, and the purge valve.


Here is the left side picture of the same thing.


The valves open up periodically under control by the car's computer. This opens up the charcoal canister to the intake which draws the gasoline vapors off the charcoal in the canister and into the intake to be burned. This process renews the charcoal so that it can continue to trap evaporating gasoline vapors. The whole idea is to reduce hydrocarbon pollution by preventing gas vapors from escaping to the atmosphere.

And here in the center of the wiring harness tray is where the two hoses from the purge valves meet up with the main hose going back to the charcoal canister. This pic is exactly how I found the hoses, disconnected.


I simply reconnected the hose with the T-connector. I'm thinking it may disconnect on its own again in which case I'll put a clamp or zip tie on it to hold it in place. I did note a bit of tension as I was reconnecting. It's possible that heat has caused a bit of shrinkage in the plastic tubing. Well, hopefully this will do it. I'll have to drive a bit to see if the P0455 code stays away. Although my car is an S600, all models will have the same parts that I have shown (just arranged differently), and disconnected or damaged hoses will be a possible cause of this fault in any car.

Brett
 

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Registered
1997 S420, 2000 E55
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255 Posts
Very nice Brett.

I will have to check this out as my problem came about right after I replaced my T-Valve. Would love my problem to be that I knocked that connection loose.

Thanks for posting.
 

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Premium Member
1997 S600 (sold)
Joined
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4,660 Posts
Discussion Starter #5
Well, I think it's fixed. After a couple of days of driving, the diagnostic check section of the OBDII diagnostics has changed from "incomplete" to "complete" for the evaporative emissions system, and no faults have come up.

Brett
 

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Premium Member
1997 S600 (sold)
Joined
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4,660 Posts
Discussion Starter #6
After ruminating on the cause of the hose disconnection for a bit, I realized that I may have caused the hoses to separate when I last changed the spark plugs.

V12 Uber Alles, Changing the Spark Plugs in a W140 Mercedes Benz

In order to more easily reach the cylinder #12 spark plug, I advocated flipping up the wiring harness tray that the evaporative emissions system tubing runs in. This action may have caused the hoses to pull apart. I cannot be certain of the timing of the spark plug change and the appearance of the P0455 fault code since it was so long ago, but they may have coincided.

If you follow my DIY article, you should check these hoses when the job is done.

cheers,
Brett
 

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16 Posts
I just wanted to write to thank Brett San Diego for his input regarding the p0455 error code. I had the exact same problem for about 6 mos now. My tech had no idea and wanted to "troubleshoot" without any research. I have been searching the forums for months and taking careful notes of my own until I discovered a satsifactory plan of action. Your diagnosis was right on and after taking the steps to reattach the hose I have had no flashing fuel light ot CEL for this entire week. Thanks for saving me time and money.
Demeterial
 

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Premium Member
1997 S600 (sold)
Joined
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4,660 Posts
Discussion Starter #8
I just wanted to write to thank Brett San Diego for his input regarding the p0455 error code. I had the exact same problem for about 6 mos now. My tech had no idea and wanted to "troubleshoot" without any research. I have been searching the forums for months and taking careful notes of my own until I discovered a satsifactory plan of action. Your diagnosis was right on and after taking the steps to reattach the hose I have had no flashing fuel light ot CEL for this entire week. Thanks for saving me time and money.
Demeterial
Always happy to help. If you're still around, what model W140? 600? And, did you have the exact same disconnection or a disconnection at a different hose junction?

Brett
 

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Registered
1997 E320 (W210)
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11 Posts
Now this is what a 'community' forum is all about. Brett - absolutely stellar job in diganoses, documentation, and sharing this info! I look forward to solving my P0455 code using this as a template (1997 E320 - W210)
 

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Premium Member
1997 S600 (sold)
Joined
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4,660 Posts
Discussion Starter #10
Now this is what a 'community' forum is all about. Brett - absolutely stellar job in diganoses, documentation, and sharing this info! I look forward to solving my P0455 code using this as a template (1997 E320 - W210)
Thanks for the kind words, and good luck tracking down your problem.

Brett
 

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Registered
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19 Posts
Brett, you are a scholar and a gentlemen

Brett Although this tread does not affect me, I think that all on this site appreciate this type of positive feedback.. Well done, Rgds

I've had the flashing gas gauge and check engine light with P0455 code for several months now. Both indicate a gross leak in the evaporative emissions control system. I finally got around to investigating the problem since I was already digging in my engine compartment to change the intake hoses and clean the throttle bodies. I think I found and fixed the problem. I was hoping it was something simple like a disconnected or damaged hose, and I did find a disconnected hose as I traced the hoses from the throttle bodies backward.

Here are some pictures:

This is the right side showing the throttle body, the evaporative emissions control system hoses which connect to the charcoal canister located in the trunk, and the purge valve.


Here is the left side picture of the same thing.


The valves open up periodically under control by the car's computer. This opens up the charcoal canister to the intake which draws the gasoline vapors off the charcoal in the canister and into the intake to be burned. This process renews the charcoal so that it can continue to trap evaporating gasoline vapors. The whole idea is to reduce hydrocarbon pollution by preventing gas vapors from escaping to the atmosphere.

And here in the center of the wiring harness tray is where the two hoses from the purge valves meet up with the main hose going back to the charcoal canister. This pic is exactly how I found the hoses, disconnected.


I simply reconnected the hose with the T-connector. I'm thinking it may disconnect on its own again in which case I'll put a clamp or zip tie on it to hold it in place. I did note a bit of tension as I was reconnecting. It's possible that heat has caused a bit of shrinkage in the plastic tubing. Well, hopefully this will do it. I'll have to drive a bit to see if the P0455 code stays away. Although my car is an S600, all models will have the same parts that I have shown (just arranged differently), and disconnected or damaged hoses will be a possible cause of this fault in any car.

Brett
 

·
Premium Member
1997 S600 (sold)
Joined
·
4,660 Posts
Discussion Starter #12
Brett Although this tread does not affect me, I think that all on this site appreciate this type of positive feedback.. Well done, Rgds
Thank you. Still no return of the fault since I posted this thread 3 years ago. I see it has gotten some mileage since then, too, with 7,500 views.

Brett
 

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Registered
1998 S600
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74 Posts
Brett you rock my friend ! Found the same problem on mine, took of the harness cover this morning and low and behold disconnected air tube from t connector. Must of tugged it when I changed my oil.
 

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GL450 2007
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11 Posts
Thank you Brett, and the others that have contributed in in fix.
I am trying to replace the Purge valve on my GL450 2007.
Reason being P0455 code.
I was able to disconnect the electric harness.
I am having trouble disconnecting the in and out tubing off the valve.
Kindly help.
Thanks
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,648 Posts
The crimp clamps will have to be cut. My best bet is to use a dremmel tool with a cut off wheel.
 

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P0455 Code solved

I had this code on a 1996 S500. I went through all the usual solutions posted on many threads without the problem being fixed - there was never any vacumm release when taking off the gas cap. I decided to learn how the system works and troubleshoot it based upon "what if" scenarios. I tested the entire system for a leak by using a vacumm pump to the lines feeding the charcoal canister, located behind the left rear wheel (you have to remove the wheel and liner, 4 10mm lugs hold it on). The line from the tank proved to have no leaks so the most common thought of the gas cap was not a problem, nor any of the other seals in the tank (good news). I tested the line from the canister to the purge valve (located on the front left side of engine compartment - no leaks here either. Tested the canister itself - no issues there either. I cleaned the purge valve with MAF cleaner - no issues there either, but I installed a new purge valve anyway since the rubber around the unit was brittle. The problem was still occurring!

Now I am asking myself what is left and this is where I wanted to know how the system works since the only other parts left are the shutoff valve ($180-$200, which is something I wanted to ensure was the fault first), or the computer module itself (ouch!). The shutoff valve is a really simple item. I took it apart as the large white piece pops off easily. Inside this area is a foam filter designed to filter contaminates from entering into the system when the valve is open. This foam had desintigrated - the car is 21 years old!

I cleaned out all the foam from the assembly with an compressed air gun. This foam filter is similar to ones used on various small engine equipment where the foam covers the paper filter. I used one I had and trimmed it to fit. I reinstalled the valve and drove the car for 30 min. I then went to the gas tank to open the cap and the vacumm had returned - problem solved for about $2!

The foam pieces were lodged in the valve diaphragm preventing a proper seal when actuated. Therefore; when the valve was suppose to close to create a sealed environment, it couldn't seal and the fault P0455 is generated. P0455 means a large leak since it cannot create any vacumm in the tank. My advice is to check this valve first on older vehicles since this is more likely to be your problem than anything else.
 

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Moderator
93 SL500, 95 SL320, 96 S320, 98 S500, 2002 E320 4Matic Wagon & A little 91 5.0 FORD Mustang
Joined
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7,949 Posts
I had this code on a 1996 S500. I went through all the usual solutions posted on many threads without the problem being fixed - there was never any vacumm release when taking off the gas cap. I decided to learn how the system works and troubleshoot it based upon "what if" scenarios. I tested the entire system for a leak by using a vacumm pump to the lines feeding the charcoal canister, located behind the left rear wheel (you have to remove the wheel and liner, 4 10mm lugs hold it on). The line from the tank proved to have no leaks so the most common thought of the gas cap was not a problem, nor any of the other seals in the tank (good news). I tested the line from the canister to the purge valve (located on the front left side of engine compartment - no leaks here either. Tested the canister itself - no issues there either. I cleaned the purge valve with MAF cleaner - no issues there either, but I installed a new purge valve anyway since the rubber around the unit was brittle. The problem was still occurring!

Now I am asking myself what is left and this is where I wanted to know how the system works since the only other parts left are the shutoff valve ($180-$200, which is something I wanted to ensure was the fault first), or the computer module itself (ouch!). The shutoff valve is a really simple item. I took it apart as the large white piece pops off easily. Inside this area is a foam filter designed to filter contaminates from entering into the system when the valve is open. This foam had desintigrated - the car is 21 years old!

I cleaned out all the foam from the assembly with an compressed air gun. This foam filter is similar to ones used on various small engine equipment where the foam covers the paper filter. I used one I had and trimmed it to fit. I reinstalled the valve and drove the car for 30 min. I then went to the gas tank to open the cap and the vacumm had returned - problem solved for about $2!

The foam pieces were lodged in the valve diaphragm preventing a proper seal when actuated. Therefore; when the valve was suppose to close to create a sealed environment, it couldn't seal and the fault P0455 is generated. P0455 means a large leak since it cannot create any vacumm in the tank. My advice is to check this valve first on older vehicles since this is more likely to be your problem than anything else.
Welcome to the forum,

I am trully happy for your fix. Really I am, and thank you for your first contribution here on this site. It will help others...

Sadly mine was not the same. My problem is not that. I too was not generating enough vacuum in the tank, and my leak was in the rubber rings that separate the upper and lower parts of the intake manifold, and in the lovely process of taking the manifold off. I BROKE TWO intake bolts(the ones that are near coolant-The rusted the threads). One I removed. The other is still stuck in there, but last week I got a one-revolution out of it using a special penetrant oil, but I am still in my saga of P0455 :frown

I'm happy for you... Here is my saga:

http://www.benzworld.org/forums/w140-s-class/2702953-mava-needs-help-p0455-gas-cap.html

All the best,

Martin
 

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Moderator
93 SL500, 95 SL320, 96 S320, 98 S500, 2002 E320 4Matic Wagon & A little 91 5.0 FORD Mustang
Joined
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7,949 Posts
Did you ever resolve your issue?
Great story btw!
Thank you. I will give you rights to my novel :laugh

It has warmed up, but I need to find some 4-Matic factory CV joint shafts as my originals(I thought were factory) have torn boots, so I need to fix my daily W210 driver before the S500.

Martin
 
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